rfw

README

Rotating File writer

An io.writer & io.Closer compliant file writer that will always write to the path that you give it, even if somebody deletes/renames that path out from under you.

Created so that Go programs can be used with the standard Linux logrotate: writes following a removal / rename will occur in a newly created file rather than the previously opened filehandle.

As the current implementation relies on remembering and checking the current inode of the desired file, this code will not work or compile on Windows.

Example

package main

import (
  "github.com/mipearson/rfw"
  "log"
)

func main() {
  writer, err := rfw.Open("/var/log/myprogram", 0644)
  if err != nil {
    log.Fatalln("Could not open '/var/log/myprogram': ", err)
  }

  log := log.New(writer, "[myprogram] ", log.LstdFlags)
  log.Println("Logging as normal")
}

TODO

• Use exp/fsnotify so that we don't need to call stat on every write
• Use exp/winfsnotify to allow for Windows support
• Trap SIGHUP and close/reopen all files
• Force a check every minute so that programs that rarely write can release filehandles

Documentation

Overview

Package rfw implements a log rotation aware file writer. It will always write to the path that you give it, even if that file is deleted or moved out from under it.

Index

• type Writer
  • func Open(path string, mode os.FileMode) (*Writer, error)
  • func (l *Writer) Close() error
  • func (l *Writer) Write(p []byte) (int, error)

Types

type Writer

type Writer struct {
	// contains filtered or unexported fields
}

A file rotation aware writer

func Open

func Open(path string, mode os.FileMode) (*Writer, error)

Open returns a new Writer at the specified path.

If the file does not exist it will be created with the specified mode. If the file does exist it will be appended to.

func (*Writer) Close

func (l *Writer) Close() error

Close our writer. Subsequent writes will fail.

func (*Writer) Write

func (l *Writer) Write(p []byte) (int, error)

Write p bytes to our file.

If our file has been deleted or has been moved out from under us, a new file will be created with the mode specified at Open time.